Conventional thermal triggering systems are produced for power switches. Here, a deflection of three bimetal strips as a result of overload currents is utilized for a switching operation. The switch is not actuated directly, but via the slide which is adapted to the position of the bimetal strips. The differential lever is pressed against the switching element by the slide and thus triggers the switching operation. The components of the switchgear have unavoidable tolerances and, in terms of their arrangement and interaction, form a tolerance chain. The effect of this has to be compensated on the ready-assembled switch. It has therefore been customary until now to make the position of the switching element adjustable. Adjustment was carried out via a fine thread screw, using which it was possible to set forward or backward a pivotably mounted carrier for the switching lever. It was thereby possible for the distance between the switching element and the differential lever to be set at a predetermined value a.
A conventional thermal triggering system for an electric switchgear is described in U.S. Pat. No. 4,691,184. The conventional thermal triggering system includes calibrating or adjusting elements.